1 Port USB to Null Modem RS232 DB9 Serial DCE Adapter Cable with FTDI - 1 x DB-9 Female Serial - 1 x Type A Male USB. Rocstor Premium 5ft FTDI USB to Null Modem Serial Adapter will change an available USB 1. 1 or USB 2. 0 port into an RS232 Null Modem serial DB9 port. This is a direct solution for DCE/DTE conflicts without needing extra cross-wired serial cables or adapters. This adapter has COM retention that will allow the same COM port value to be re-assigned to the port in the event that the cable is removed and re-connected to the host computer or if the system is rebooted. The integrated FTDI chipset supports additional customization, advanced features, and compatibility not necessarily offered by other solutions. It is compatible with many operating systems including Windows? Windows CE, Mac OS and Linux. Backed by Rocstor 2-Year .